The desire to look young and healthy is universal. Primary attributes of young and healthy-looking skin are evenness of skin color and texture. Uneven skin color and texture is the result of one or more imperfections: lines and wrinkles, blotches and age spots, visible pores, etc. Assessment of the efficacy of compositions to correct imperfections of the skin is an important part of the activity in the development of skin products. One commonly used method for assessment of the blemishes is through use of professional clinical graders. In this method trained clinicians grade the improvement of the skin appearance over extended use of the product. This assessment is subjective and expensive. Hence there have been many attempts to use instrument based image analysis methods to objectively grade the skin appearance. See for instance EP 516 457 (Unilever); WO 2008/028893 (Unilever); Hillebrand et al., U.S. Pat. No. 6,571,003; Rubinstenn et al., U.S. Pat. No. 6,761,697; Attar et al., U.S. Pat. No. 6,734,858; Hawkins et al., U.S. Pat. No. 6,959,119; Takano et al., U.S. Pat. No. 6,091,836; U.S. Patent Application No. 2004/0261280; and U.S. Patent Application No. 2007/0086651 A1; JP 2007-252891 and JP 2002-330943 (abstracts).